Xenon lamps are known for providing extremely high intensity lighting, particularly for stadium, theatrical and film projector applications. Xenon lamps carry xenon gas under high pressure in an elongated glass envelope, usually made of quartz glass. The light given off from the high pressure xenon has a close resemblance to sunlight in terms of the spectral distribution of light given off under normal electrical load.
Inside the glass envelope, a cathode is situated opposite an anode a proper distance to maintain an arc. The cathode is kept small to insure that its temperature will be sufficiently high, at its rated current, to emit the electrons necessary to sustain the arc.
The power supply is typically a direct current power supply including an ignition device. The operating voltage of such lamps is from about 15 volts for lamps of about 75 watts, up to about 65 volts for lamps of about 10,000 watts. Consequently, the current for such lamps, following ohms law, is about 5 amps for a 75 watt lamp and about 153.8 amps for the 10,000 watt lamp.
Although some variations on the configurations of the lamps are known, the higher wattage lamps have required a bolt and nut, cable type connection. With this type of connection, electrician's tools are required to replace the lamps which have failed. In some cases, cable pig tails are provided from metal sleeves used to strengthen the conductor transition into the glass envelope. The cable pig tails may be fitted with lugs having eyelets for the engagement of the lugs using electrically rated bolts. A wrench is needed to ensure good, tight electrical contact. The labor expenditure in changing spent bulbs is therefore significant, requiring specialized tools.
In some of the lower current configurations, the lamps may be fitted with an end portion having a fine threaded end adjacent a knurled nut. The knurled nut is used to rotate the fine threaded end into engagement with a threaded lug at the end of a cable. Currently, the maximum power ratings of lamps which employ such connective structures are on the order of no more than 4000 watts.
One of the reasons that the knurled nut is used with a finely threaded member in the lower current configurations, is the necessity for lamp clearance during installation and removal. The threaded male members may be attached to the female members while the lamp is mounted generally in the position to which it will rest during operation. Since the conductors are located at the opposite ends of the lamp, the current configuration would not permit a xenon lamp, even one of low current, to be screwably mounted like a standard light bulb. A light bulb with two, oppositely oriented threaded ends would not permit a standard light bulb-type socket to be utilized.
What is needed is a configuration which will facilitate the changing and installation of high power lighting, especially xenon lamps. The configuration should include a fitting for the lamp and the electrical conductor to which it is to be connected which will allow for hand mounting of the lamp.